import matplotlib.pyplot as plt
import numpy as np

plt.plot([1,2,3,4],[2,8,4,1],'o-r', label="Line A")
plt.plot([1,2,3,4],[3,9,5,2],color='black', marker='v', label="Line B")
plt.title('test')
plt.xlabel('xlabel')
plt.ylabel('ylabel')
plt.xlim(0,10)
plt.ylim(0,20)
plt.xticks(np.arange(0,11,2),['a','b','c','d'])
plt.legend()
plt.show()
